1. Field of the Invention
This invention relates to an image sensing apparatus and to a method of controlling the operation of this apparatus.
2. Description of the Related Art
There are instances where a camera is equipped with an image stabilization function in order to reduce blurring of images due to camera shake.
The description set forth in Patent Document 1 deals with the prevention of stretching that occurs at the periphery of a captured image, owing to optical aberration of the lens, when optical image stabilization is carried out. When camera shake is sensed by a gyro sensor, an offset correction quantity is calculated by a correction calculation circuit and a shake correction is applied optically based upon the calculated offset correction quantity, a reference position is moved within the shooting zone based upon correction vector data indicative of correction direction and correction quantity, and a per-pixel distortion correction is performed on the basis of the moved reference position.
Further, the description set forth in Patent Document 2 deals with accurate restoration of an image by eliminating effects of image distortion in an imaging lens system. Image deterioration information from the optical system is stored in memory, camera shake at shooting time is detected and a time-series camera-shake detection signal is stored in memory, the image data is corrected based upon the optical-system image restoration information and, by using the image data that has been corrected by the image deterioration information, the deterioration of the image data due to camera shake is restored based upon the camera-shake detection signal, whereby restoration of the image, from which the effects of optical-system image deformation have been eliminated, is carried out. The system described in Patent Document 2 provides a circuit for calculating an image restoration function in order to restore image deterioration due to camera shake. The image restoration function is output upon predicting, from the output of a fundamental path calculation circuit, how the original image will change.
Further, the object of Patent Document 3 is to provide a camera, which is equipped with a blur correction function, in which a blur correction can be carried out so as to render inconspicuous a difference in amount of image offset, between screen center position and periphery position during exposure, owing to factors such as the size of the angle of view of the shooting lens. This system finds a correction limit value Δh, which is for when a blur correction is performed in the camera body, in the flash ROM of a lens unit, and limits the amount of shift of an image sensing device at the time of the blur correction. In other words, this system, rather than performing a distortion correction, detects and avoids areas of great distortion.
Patent Document 1: Japanese Patent Application Laid-Open No. 2006-129175
Patent Document 2: Japanese Patent Application Laid-Open No. 2006-33759
Patent Document 3: Japanese Patent Application Laid-Open No. 2007-233166
When image stabilization is carried out, optical distortion and shading and the like can differ frame by frame owing to such factors as direction of camera shake and amount of camera shake, and there are instances were a moving image develops image distortion. In Patent Document 1, however, no consideration is given to image stabilization that strokes in a complex manner within one frame. Further, in Patent Document 2, optical-system image distortion cannot be corrected merely by recording a camera-shake detection signal, and no correction is made for image distortion in an optical system that has been affected by time-series camera shake. Furthermore, in Patent Document 3, a correction based upon camera-shake information frame by frame is not carried out even below the distortion correction limit. Thus, the problems of image distortion and of image distortion in a moving image due to image stabilization cannot be solved by any of Patent Documents 1 to 3.